1. Field of the Invention
The present invention relates to an air-purifying device for vehicles and particularly to an air-purifying device for vehicles capable of purifying ozone in atmospheric air.
2. Description of the Related Art
In prior-art air purifying using an ozone purifier having a function of purifying ozone, function deterioration caused by long-term use has been known, and various researches/development have been made regarding diagnosis of this function deterioration. For example, Japanese Patent Laid-Open No. 2001-347829 discloses an air-purifying device for vehicles in which an ozone concentration sensor is provided on the front and rear of a radiator in which an ozone purifier using manganese carbonate and manganese oxide as main components is provided, and function deterioration of the ozone purifier is diagnosed by using their sensor outputs. In this air-purifying device, if a ratio of outputs between the sensors on the front and the rear of the radiator falls to approximately a half of an initial value (a ratio of outputs of the both sensors at shipment), it is diagnosed that the function of the ozone purifier has deteriorated.
However, ozone concentration in the air is generally as low as 1 ppm or less. Thus, in order to detect ozone concentration by using a sensor, a sensor with high accuracy is required. Thus, with Japanese Patent Laid-Open No. 2001-347829 in which an ozone concentration sensor is provided on the front and rear of the radiator, there is a problem that a cost increase caused by mounting sensors cannot be avoided.